Directed by Lee Jang-soo, the creator of the popular TV series "Stairway to Heaven," the new drama features a heart-wrenching love story between actor Lee Wan and actress Park Shin-hye, who had played little Shin Hyun-joon and Choi Ji-woo in Lee’s previous dramas.

Designed to match the taste of Japanese viewers, characters in the drama – most played by Japanese actors and actresses – frequently converse in Japanese, confusing local viewers over whether the drama is really Korean.

Lee Wan (left) and Park Shin-hye in SBS drama "Tree of Heaven"

But at the same time, the drama faithfully follows a popular Korean drama formula, portraying a forbidden romance between a devoted hero and a pitifully kindhearted heroine. Japanese sports daily, Sankei Sports, recently predicted the drama’s success in Japan saying, "As another one of Korea’s heartbreaking romances made by talented director of ‘Stairway to Heaven,’ the drama is expected to make another major impact here."

The new drama appears to be an outcome of the drama-maker’s effort to overcome the cooler response from neighboring countries toward Korean dramas.

Starting with "Winter Sonata," Korean dramas became the main contributors to the Korean Wave and were also guaranteed moneymakers.

But a few years later, the boom began to diminish in Japan, Taiwan and other Asian countries, with many new Korean dramas failing to arouse the same interest. No actor or actress succeeded in becoming the second Yonsama – actor Bae Yong-joon. Although Korean dramas are still popular overseas, with their exports steadily growing, many critics stress the need of a major renovation in the Korean drama making system to maintain the current Korean Wave.

Thus, TV critics regard "Tree of Heaven" as an encouraging tryout in finding a new profitable model for Korean dramas.

"It has been proven that Japanese viewers have a soft spot for corny romances. The new drama is an encouraging tryout to see if adapting more to the Japanese style, while filling the desire for corny romances, will work to keep up the popularity of Korean dramas," said critic Chung Han-pyo.

Despite that positive view, many local TV viewers have been criticizing the "Tree of Heaven" for its excessive use of the Japanese language and overflow of Japanese sentiment.

Because the drama is so Japanese, it fails to emphasize the distinctive features of Korean dramas which have been the main driver for the Korean Wave, they assert.

"I felt like I was watching a Japanese drama with a few Korean actors and actresses appearing on it," said internet user jung9965 on the drama’s website after the first episode was aired. "I don’t understand why I have to make an effort to keep up with the Korean subtitles while watching a drama made by my own country."

Internet user Nurikkun agreed.

"If the producers cared about the Japanese TV fans enough to ignore Korean viewers completely, what’s the point in airing it in Korea? I am very doubtful that Japanese viewers will fall for this drama which is neither Korean nor Japanese."

Regardless of the criticism, "Tree of Heaven" is showing steady growth in viewer ratings with its leading actor and actress receiving much attention in both Korea and Japan.

Park Shin-hye, who just turned 16, is highly praised for her talented acting in which she speaks the Japanese lines fluently despite the fact that she has never lived in Japan or learned the language.

"Many Japanese commercial-makers and production companies have contacted us, wanting to sign contracts with Park," said Park’s agent. "We are happy with the proposals, but because Park has just begun acting, we are planning to be prudent with her entering the overseas entertainment world."

And actor Lee Wan, 23, who had at first received more attention as the younger brother of top actress Kim Tae-hee, is also enjoying compliments for improved acting skills.

"Many Japanese broadcasters have been showing immense interest in Lee after hearing news that ‘Tree of Heaven’ will also be aired in Japan. And many Korean filmmakers and producers have also been contacting us," said an official at Lee’s agent, Logos Film.